Corrosion inhibiting method and composition



United States Patent O F CORROSION INHIBITING METHOD AND COMPOSITION Willard R. Scott, Alhambra, and Bruce L. Garner, La Habra, Calii, assignors to California Research CDOLJOI'BfiOII, San Francisco, Calif., a corporation of e ware No Drawing. Application September 29, 1953,

Serial No. 383,141

6 Claims. (Cl. 252-855) This invention relates to a composition and method 15 for inhibiting corrosion of ferrous metals such as iron, steel and ferrous alloys. The composition and method described herein inhibit the corrosive attack of acids and oxidizing agents on ferrous metals and are particularly effective in the corrosive environments in producing oil wells where ferrous metal tubing, casing, and the like,

are in contact with a production stream comprising brine,

oil and carbon dioxide.

2,785,126 Patented Mar. 12, 1957 where both Rs are alkyl groups would undergo a conventional chemical reaction-with carbon disulfide, and thus the products obtained by intimately mixing this type of imidazoline with carbon disulfide may be a molecular compound. Imid-azolines of the type:

N--OH: 3-0:

in which the l-nitrogen atom is present in a secondary amino group, apparently form dithiocarbamic acids of the type:

N-OH: R-Qf l The corrosion inhibitors of this invention are the prod V ucts obtained by intimately mixing an imidazoline with approximately equimolar quantities of carbon disulfide. A wide variety of imidazolines have been mixed with carbon disulfide and in all instances the products have shown extraordinary capacities to inhibit corrosion ferrous metals when incorporated in the corrosive medium in contact with the'ferrous metal at very low concentrations. Every compound tested containing the imidazoline ring, i. e., r

combined with carbon disulfide to yield an efficient corrosion inhibitor. The group bonded to the imidazoline ring at the 2-position appears to exert relatively little influence on the corrosion inhibiting capacity'of the imidazoline-carbon disulfide product. In other words, the effectiveness of the corrosion inhibitor is little influenced by the selection of the carboxylic acid employed to react with the polyamine to producethe imidazoline. 'The i radical bonded to the imidazoline ring in the 1-position 6' 1 has appreciably greater efiect on the inhibiting efiectiveness of the imidazoline-carbon disulfide product.

The nature ofthe interaction of the imidazolines with I carbon disulfide is not entirely clear. It wouldnot be expected that an imidazoline of thetype; 7

N-CH:

K -l if or the imidazoline salt of this acid. When heated, these in which a primary or secondary alkyl-amino radical is bonded to the imidazoline ring at the 1-position react with carbon disulfide forming dithiocarbamic acids, such or the corresponding imidazoline salt. Considerable heat is evolved during the reaction of this type of imidazoline with carbon disulfide, and the resulting products decompose when heated, yielding hydrogen sulfide.

Pursuant to the invention, the 1-position of the imidazoiine ring may be occupied by a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an alkaryl group, an amino group, an alkyl amino group, a hydroxy alkyl group, and the like. It is preferred to employ imidazolines in which the l-position is occupied by either hydrogen, an alkyl group, or an amino-alkyl group, since imidazolines containing these structures are readily and cheaply synthesized. The 2-position of the imidazoline ring is occupied by the residue of the carboxylic acid which is condensed with the diamine to form the imidazoline by splitting out two molecules of water. Thus, the 2-position may be occupied by alkyl groups contain ing 1 to 30 carbon atoms, hydroxy alkyl groups containing 1 to 30 carbon atoms, halogenated alkyl groups containing l to 30 carbon atoms, sulfatoxy alkyl-or 'alkenyl groups, phosphatoxy alkyl or alkenyl groups, aryl groups such as phenyl or naphthyl when benzoic acid or naphthoic acid is condensed with the amine and substituted aryl groups. p V v The compositions of the invention are prepared by slowly adding the imidazoline to carbon disulfide at a temperature in the range from about to 30 C., cooling the mixture as necessary to dissipate any heat of reaction. In some instances the preparation of the inhibitors is facilitated by dissolving the reactants separately in a volatile solvent such as a low molecular weight alcohol, for example, methanol, and then mixing the two solutions. The products vary considerably in physical appearance, ranging from tacky viscous oils to waxy or rosin-like solids.

A large number of imidazolines were reacted with approximately equimolar quantities of carbon disulfide and the products were tested at varying concentrations as corrosion inhibitors. The corrosive environment employed was a brine containing 30 grams per liter of sodium chloride, saturated with carbon dioxide and containing bubbles of gaseous carbon dioxide. In some cases brineoil mixtures containing carbon dioxide were employed. The concentrations of the corrosion inhibitors reported below are in parts per million based on the water content of the corrosive environment into which they were injected. The corrosion measurements were made pursuant to the method described by Scott and Rohrback in Corrosion, July 1952, page 234 et seq. In the following tables the parent compound is the imidazoline with which carbon disulfide was mixed to produce the claimed corrosion inhibitors. The carbon disulfide derivative-as shown in the tables is the product obtained by mixing the parent imidazoline with approximately an equimolar quantity of carbon disulfide.

Parent Compound GS: Derivative Parent Compound Brine Brine cone, Only, Cone, only, p. p. 111 Percent p. p. 111. Percent Inhibi- Inhibinon tion A. Compounds derived from ethylene diamine and carboxylic acids: 50 84, 89 1. 2-Methylimidezoline 50 0 26 67 5 5s C s* l (amber vitreous liquid) 50 77, 87 2. 1-0ctadecyl-2-methyltmidazoiine so 64 -N- 0. 5 7

on i

(amber solid) 3. 2-Heptyiim1dazoline 8 88 5 17 (brown tar) V 4. 2-Undecyclim1dezoline 50 0,9 v g g:

, N- C11H2P l (yellowish solid) 15. 2-(Hydroxyheptadecenyl)-imidazoline 150 N i1Hes0) f; e. Z-Trldeoyiimidezoline '50 '10 to uH2v Parent Compound s, Derivative 1 Brlne Oil Present Oll Present Parent Compound 0onc., Only, Oonc., Brlne Only,

. v p. p. m. Percent p. p. m. Percent Inhib- 011/ Percent Inhibition 011/ Percent tlon Water Inhibl- Water Inhlbltlon tlon B. Oomnounds derived fl'om dlethylenetriemine:

1. 1-Amlnoethyl-2-hepty11mldazollne 50 0 150150 0 86 .5 77

HICHINHl v 2. 1-Amlnoethyl-Z-undecyllmldazollne e7 5 11 g O11H|r N V v 100 50 50 (:mcnmm go B 80 a. 1 Aminoethyl2-h6ptnd6c8nyllmld8z01lm 50 0 m 50/60 75 N z /50 ea 0 5 61,49 u On u (JHgCHlNHI 50 77, 84, 88 4. l-Aminoethyl-2-(hydmxyheptadecenyD-imldazollne 50 59 5 0 0 g 7731,32 /60 82 (SHaCHzNH, (viscous yellowish glass) 5. 1-Amlnoethyl-2-(sullatoxyheptadecenyl)-lm1daz01lno 50 50 79 3H, CHsN H: (tacky yellow solid) 6. l-Aminoethyl-2-(phosphatoxyheptadecenyl)dmldazoline, sodium salt-. 50 44 N 5 o 0 (CuHuO P OaNa N JHlCHgNHg (yellow wax) 0. Compounds derived from triethylenetetramine:

1. l-(aminoethylamlno)-ethyl-2-heptadecyllmldazoll 100 50/50 44 J1H| CH:NHCH5 CHg-NH; 2. 1-(2-aminoethylemino)-ethyl-2-(hydroxyheptadecenyl)-lmldazoline-. 4

&HjCHI-NHC HflCHi-NH (viscous black oll) D. Compounds derived from tetraethyleneentamine:

l. 1[2-(aminoethylamlne)ethylamlno -2(hydroxyheptadecenyl)- imidazoline 41H: CHr-NH- CH1 C Hr-NH- C H] C Hg-N H! E. Miscellaneous compoun 'a-mS HaOHIOH The corrosionjiirhibitors of the invention may be intro- If desired, the inhibitors canbe:

clay to form a dense solid which can be dropped through the tubing to the bot-tom of the well.

It is evident from the data shown in the tables above that the inhibitors of the invention are highly etfective at low concentrations and since they are sparingly soluble in water, adequate protection against corrosion can be obtained by treating the wells periodically at intervals of several days.

We claim:

1. As new compositions of matter, the products obtained by intimately mixing a compound containing the structure:

ITI- CHI with an approximately equimol'ar quantity carbon disulfide.

2. As a new composition of matter, the product obtained by intimately mixing an imidazoline with an approximately equimolar quantity of :c arbon disulfide at low temperatures.

3. The composition as defined in claim 1, wherein the l-nitrogen atom of the imidazoline ring is bonded to three carbon atoms.

4. The composition as defined in claim 1, wherein the l-nitrogen atom of the imidazoline ring is a secondary amino nitrogen atom.

5. As a new composition of matter, the low tempera- 'ture reaction product of a 1-(amino-alkyl)-imidazoline with carbon disulfide. V

6. The method of preventing corrosion of ferrous metal tubing in an oil well delivering a production stream comprising crude oil, brine, and carbon dioxide gas which comprises introducing the product obtained by intimately mixing at low temperature an imidazoline with an approximately equimolar quantityof carbon disulfide into the well bottom.

References Cited in the file of this patent UNITED STATES PATENTS 2,453,881 Viles et al. Nov. 16, 1948 2,461,359 Viles et al. Feb. 8, 1949 2,466,517 Blair et a1. Apr. 5, 1949 2,468,163 Blair et al Apr. 26, 1949 2,503,059 Miescher et al, Apr. 4, 1950 2,505,248 Isler et a1. Apr. 25, 1950 2,574,576 Marsh Nov. 13, 1951 2,723,232 Scott Nov. 8, 1955 

1. AS NEW COMPOSITIONS OF MATTER, THE PRODUCTS OBTAINED BY INTIMATELY MIXING A COMPOUND CONTAINING THE STRUCTURE:
 6. THE METHOD OF PREVENTING CORROSION OF FERROUS METAL TUBING IN AN OIL WELL DELIVERING A PRODUCTION STREAM COMPRISING CRUDE OIL, BRIME, AND CARBON DIOXIDE GAS WHICH COMPRISES INTRODUCING THE PRODUCT ONTAINED BY INTIMATELY MIXING AT LOW TEMPERATURE AN IMIDAZOLINE WITH AN APPROXIMATELY EQUIMOLAR QUANTITY OF CARBON DISULFIDE INTO THE WELL BOTTOM. 